I was wondering if you could tell me why my brakes stick. I just got some new drum brakes for my Honda XR100 not too long ago and they shouldn't be bad yet. Whenever I shove down on the rear brake it stops me, but it sticks and I have to play with it before it pops back up.
The most common reason a rear brake sticks on is wear. The brake shoes ride on a post on one side, and the flat ends of the shoes ride on a flat on the other side. The rear brake actuating arm is attached to the flat. When you put on the rear brakes, the rear brake pedal twists the flat sideways, and that forces the brakes shoes apart, and causes them to rub on the brake drum. That friction between the drum and shoes are what makes the bike stop. If the shoes are undersize, the flat can turn sideways, and it usually sticks sideways since the brake rod is pulled at such a radical angle to pull the flat all the way sideways.
If the shoes are new, they should not be undersize. If they are not Honda parts, I'd suspect that the aftermarket brake shoes are not made correctly. If the shoes are Honda parts, and they don't show wear, then the drum is worn. A Honda dealer should be able to tell you the service limits on the shoes and the drum. If everything measures out fine inside the drum, check to see that the pivots are moving freely. The brake actuating arm bolts to a round, splined shaft that extends through the rear brake backing plate. On the other side of the plate, the shaft is machined flat, and that flat opens the shoes. If the backing plate is worn, or the shaft is galled or dry, the brake can stick. That shaft does need grease, but you have to be careful not to get too much grease on it. You don't want it working into the drum. The same is true of the pivot of the brake pedal itself. Disconnect the pedal from the drum, and see if it is moving freely. That pivot should get regular grease applications (you don't need to be so careful).
Finally, chack and make sure that the brake rod isn't bent in some way that is making the rear brake hang up on something. If you are careful and methodical, you should find the problem.